1. Field of Invention
The present invention relates generally to vehicle seats and, more particularly, to vehicle seats having self-powered back supports, leg rests and foot rests.
2. Description of the Related Art
Vehicle seats, such as those found on airplanes and trains, commonly include a substantially horizontal thigh and buttock support (hereinafter "thigh support") and a back support which pivots about an axis adjacent to the rearward portion of the thigh support. The back support may be reclined from an upright position, through any number of intermediate positions, to a substantially horizontal fully reclined position. Vehicle seats also commonly include leg rests which pivot about an axis adjacent to the forward portion of the thigh support. The leg rest may be pivoted from a substantially vertical storage position, through any number of intermediate use positions, to a substantially horizontal, fully extended use position. In the intermediate and fully extended use positions, the leg rest will provide support for the lower legs of an average sized passenger, from approximately the knee to the ankle. When a passenger is ready to sleep, the back support may be moved to the fully reclined position and the leg rest may be moved to the fully extended use position. Oriented in this manner, the seat will provide a comfortable sleeping surface.
More extravagant seats, such as those found in the first cabin (or first class) section of an airplane, also include a foot rest which is associated with the leg rest. Such foot rests are commonly movable from a retracted non-use position behind the leg rest, through any number of intermediate use positions, to a fully extended use position. In a use position, the foot rest effectively increases the length of the leg rest so that the leg rest will support the passenger's feet as well as his or her lower legs. There are a number of considerations which mitigate against simply employing a longer leg rest that will also support the feet. For example, not all passengers desire foot support. In addition, the length of the leg rest must be less than the distance between the pivot axis associated with the thigh support and the floor of the vehicle to which the seat is secured. A leg rest that is longer than this distance would not be able to pivot to its substantially vertical storage position because it would strike the floor before reaching that position.
Lumbar supports are another common luxury item associated with more extravagant seats. Such lumbar supports are typically capable of adjustment both up and down along the length of the back support and toward and away from the back support.
Many vehicle seats, including the more extravagant seats described above, also include self-powered electro-mechanical actuators which move the back support and leg rest, as well as the foot rest and lumbar support if included on the seat, to the orientation desired by the passenger. Such self-powered seats typically include a control panel having a variety of buttons, knobs or other similar implements associated with the movable portions of the seat. When, for example, a button corresponding to the back support is pressed, a switch will close and the back support will slowly recline until the button is released or the back support reaches its fully reclined orientation. Similarly, when another button corresponding to the back support is pressed, the back support will slowly incline until the switch is released or the back support reaches its fully upright orientation. The other movable portions of the seat are controlled in a similar manner.
There are, however, a number of disadvantages associated with the conventional vehicle seats described above. For example, passengers often return the leg rest to its storage position before returning the foot rest to its non-use position. As the combined length of the leg rest and extended foot rest is usually greater than the distance between the rotation axis associated with the forward portion of the thigh support and the floor of the vehicle, the foot rest will be forced into the floor before the leg rest reaches its storage position. The seats are often damaged as a result.
Another disadvantage associated with conventional vehicle seats has to do with the number of steps required to adjust the seat to the sleep position, where the back support is fully reclined, the leg rest is fully extended and the foot rest is extended, or to the fully upright position, where the back support is upright and the leg rest and foot rest are in their respective storage and non-use positions. The passenger must determine whether each movable portion of the seat is in the desired position and, if any are not, individually adjust those portions by finding and engaging the appropriate button or knob. This is obviously quite inconvenient.